How do I make a repeat entry of a gig?

For regular events, a quick and easy way to create a repeat entry of a past gig is to change the date of an archived gig.

Just open the page of the archived gig, click edit and change the date. It's not really copying the event but just moving it out of the archives.
To find an archived gig, select MY GIGS from the PROFILE menu dropdown on the top of the page. 
On the top right you'll see the Show Archive icon. Click that and it will show the archived events. Open the gig from the list that appears below. On the gig page, click edit (the icon next to "Gig" under the title) and change the date.